将GMT时间转换为本地时间。

I got current GMT time - 2013-05-15 08:55 AM

我现在是格林尼治时间- 2013-05-15 08:55

my current local time is - 2013-05-15 02:06 PM and time zone is - Asia/Kolkata

我现在的本地时间是- 2013-05-15 02:06 PM和时区是- Asia/Kolkata。

I tried to convert the above GMT to my local time with this code

我试图用这个代码将上面的GMT转换为本地时间

   NSTimeZone* sourceTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"Asia/Kolkata"];
   [dateFormatter setTimeZone:sourceTimeZone];


      // timeStamp - is the above GMT time

   NSDate *dateFromString = [dateFormatter dateFromString:timeStamp];
    NSLog(@"local time is %@",dateFromString);

but this give me wron time as - 2013-05-14 19:04:00 +0000 instead of 2013-05-14 02:06 PM

但是这给了我时间- 2013-05-14 19:04:00 +0000而不是2013-05-14 02:06

Why this happens? please help me to clear this.Thanks in advance

为什么发生这种情况呢?请帮我清理一下。谢谢提前

5 个解决方案

#1

Nothing is going wrong, a NSDate instance will never have a timezone ( well it will but it is always GMT, indicated by the +0000 timezone in the date description).

没有什么出错，NSDate实例永远不会有时区(当然会，但它总是GMT，日期描述中+0000时区表示)。

What you are telling dateformatter in your code is that the timezone of the date you want to parse is Asia/Kolkata but you want it to be GMT.

您在代码中告诉dateformatter的是您希望解析的日期的时区是Asia/Kolkata，但您希望它是GMT常量。

First you need to make a NSDate object from the input date string with the time zone set to the correct time zone, GMT as you indicated.

首先，需要从输入日期字符串中创建一个NSDate对象，将时区设置为正确的时区，如您所示的GMT。

NSTimeZone *gmtTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
[dateFormatter setTimeZone:sourceTimeZone];
NSDate *dateFromString = [dateFormatter dateFromString:timeStamp];
NSLog(@"Input date as GMT: %@",dateFromString);

Then when you present the date as an string use :

然后当你用字符串表示日期时:

NSTimeZone* sourceTimeZone = [NSTimeZone timeZoneWithName:@"Asia/Kolkata"];
[dateFormatter setTimeZone:sourceTimeZone];
NSString *dateRepresentation = [dateFormatter stringFromDate:dateFromString];
NSLog(@"Date formated with local time zone: %@",dateRepresentation);

#2

The shortest way that I found to convert GMT time to your local timezone is

我发现将格林尼治时间转换为当地时区的最短方法是

 NSDate* localDateTime = [NSDate dateWithTimeInterval:[[NSTimeZone systemTimeZone] secondsFromGMT] sinceDate:dateInGMT];

Furthermore, to convert this date value into string

此外，将这个日期值转换为字符串

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"HH:mm:ss"];//use the formatted as per your requirement. 

//Optionally for time zone converstions
[formatter setTimeZone:[NSTimeZone timeZoneWithName:@"..."]];

NSString *localTimeDateString = [formatter stringFromDate:localDateTime];

#3

NSLog(@"local time is %@",[dateFormatter stringFromDate: dateFromString]);

#4

NSTimeZone* gmtTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
NSTimeZone* localTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"Asia/Kolkata"];

NSDateFormatter *gmtDateFormatter = [[NSDateFormatter alloc] init];
[gmtDateFormatter setTimeZone:gmtTimeZone];

NSDate *date = [gmtDateFormatter dateFromString:timestamp];

NSDateFormatter *localDateFormatter = [[NSDateFormatter alloc] init];
[localDateFormatter setTimeZone:localTimeZone];

NSLog(@"local time is %@",[localDateFormatter stringFromDate:date]);

#5

Use timeZoneWithName

使用timeZoneWithName

NSDate *date=[[NSDate alloc]init];
NSDateFormatter *timeFormat = [[NSDateFormatter alloc] init];
[timeFormat setTimeZone:[NSTimeZone timeZoneWithName:@"Asia/Kolkata"]];
[timeFormat setDateFormat:@"HH:mm"];
NSString *dateStr=[timeFormat stringFromDate:date];

#1